Apparatus for tensioning a fabric during knitting



nited States Patent 0 3,417,581 APPARATUS FOR TENSIONING A FABRIC DURING KNITTING Jaroslav Docekal and Miloslav Losert, Trebic, Czechoslovakia, assignors to Elitex, zavody Textlniho Strojirenstvi Reditelstvi, Liberec, Czechoslovakia Filed July 21, 1966, Ser. No. 567,336 10 Claims. (Cl. 66-147) ABSTRACT OF THE DISCLOSURE Rotating tensioning members are mounted for axial movement into the needle cylinder for tensioning the knitted fabric during working strokes under the action of springs, and are moved in return strokes 'by stationary cam means while releasing the fabric.

The present invention relates to apparatus for tensioning a fabric during knitting on a circular knitting machine, particularly on a double cylinder knitting machine.

Fabrics knitted on a circular knitting machine pass through the needle cylinder into a container. It is known to draw the knitted fabric into the container by means of a pair of knurled rollers, which has the disadvantage that the rollers act at a great distance from the cylinder needles. Furthermore, successive lengths of knitted fabric have to be connected to each other to permit a continuous operation of the transporting rollers.

It is also known to use blowers or fans for producing air streams urging the knitted fabric into a tensioned condition and toward the receiving container. However, this apparatus has a very low efliciency, and the power consumption of the blower drive is comparatively high.

It is one object of the invention to overcome the disadvantages of known apparatus for tensioning and transporting a fabric knitted on a knitting machine, and to provide a compact, simple, and eflicient apparatus for tensioning the knitted fabric.

Another object of the invention is to provide apparatus for tensioning a fabric knitted on a knitting machine by reciprocating tensioning members which during a working stroke engage the fabric, and during a return stroke release the fabric.

Another object of the invention is to provide a plurality of tensioning members which are sequentially actuated to tension the knitted fabric.

Another object of the invention is to provide apparatus for tensioning the fabric knitted on a circular knitting machine which can be placed in an inoperative position or in an operative position, as desired.

Another object of the invention is to tension a knitted fabric by working strokes of reciprocating tensioning members, and to hold the fabric during the return stroke of the tensioning members so that the fabric does not follow the same.

With these objects in view, the present invention relates to an apparatus for tensioning a knitted fabric, which is preferably combined with a circular knitting machine having a rotating needle cylinder.

One embodiment of the invention comprises support means on the knitting machine; guide means mounted on the support means for rotation about the axis of the needle cylinder and being rotated from the same; fabric tensioning means mounted on the guide means for axial reciprocating movement, and projecting into the needle cylinder so as to engage the fabric and tension the same during a working stroke, and to release the same during a return stroke; and operating means for reciprocating the tensioning means.

In the preferred embodiment, the tensioning means include a plurality of tensioning elements, each of which includes a guide member mounted in the guide means for axial movement, and a tensioning member pivotally mounted on the respective guide member for angular movement between an inner position and an outer position engaging the fabric in the needle cylinder. The operating means includes a plurality of springs respectively secured to the tensioning members and to the guide means for urging the tensioning members to the outer position engaging the fabric, and simultaneously urging the entire tensioning element to move in the tensioning direction so that the fabric is tensioned when engaged by the pointed ends of the tensioning members. While the springs effect the working strokes of the tensioning elements, the same are retracted in return stroke by a stationary cam means along which cam followers on the respective guide members move during rotation of the guide means with the needle cylinder. The stationary cam means is preferably secured to a support shaft on which the guide means and tensioning means are mounted for rotation. The support shaft can be raised and lowered by control means so that the entire apparatus can be placed in an inoperative position or in an operative position, as desired.

Holding means, preferably including a circular row of pointed projections, are provided for preventing a movement of the fabric with the tensioning members during the return strokes of the same.

Due to the successive engagement of the cam followers by projecting portions of the cam, the tensioning members are successively operated to act on circumferentially spaced portions of the tubular fabric which is knitted on a circular knitting machine and passes through the needle cylinder of the same. It is possible to form the cam means in such a manner that each of the tensioning members advances the knitted fabric a different distance.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of a specific embodiment when read in connection with the accompanying drawing whose single figure is an axial sectional view illustrating the head and needle cylinder of a double cylinder circular knitting machine provided with an apparatus according to the invention.

Referring now to the drawing, a circular knitting machine includes a stationary support 30, and a needle cylinder 22, 220. A fabric is knitted by the needles in the usual manner and moves in the form of a tube 31 into the interior of the needle cylinder in downward direction to be collected in a container, not shown.

A support plate 10 is mounted on vertical bolts 10a, and carries a sleeve 8 in which a support shaft 7 is mounted for axial movement, but secured by a key 9 against rotation in sleeve 8. A coil spring 21 abuts a shoulder in sleeve 8 and a flange on shaft 7 to urge shaft 7 to an upper position. A lever 20 is pivotally mounted on a bracket 10b on support 10, and is connected with a Bowden cable 19 which can be manually operated to turn lever 20 in clockwise direction to the position shown in the drawing. When Bowden cable 19 is released, spring 21 urges support shaft 7 and lever 20 upward.

Support shaft 7 has a flange portion 7a and rotatably supports a guide means in the form of a bushing 1 which is connected by a key with a tube 2 for rotation. Tube 2. is secured to the needle cylinder for rotation so that guide means 1 is rotated by the needle cylinder 22, while key 4 permits axial movement of guide means 1 together with support shaft 7.

Guide means 1 has a plurality of guide ways formed by aligned bores in flanges of guide means 1, and in each guide way, a guide member 3 is mounted for axial movement parallel to the axis of support shaft 7, guide means 1, and needle cylinder 22. Each guide member 3 carries a rotary cam follower 5 cooperating with a cam 6 secured to support shaft 7 and having projecting means which successively engage cam followers 5 during rotation of guide means 1 with guide members 3 about support shaft 7. Consequently, guide members 3 are reciprocated in axial direction during each revolution of guide means 1 about support shaft 7 and relative to cam means 6.

Each guide member 3 has at the lower end a pivot 11 on which a tensioning member 12 is mounted for angular movement between a radially inner position, and a radially outer position. In the outer position shown for tensioning member 12 in the left portion of the drawing, a pointed end portion or pin 13 is in contact with the knitted fabric 31.

A spring 15 urges each tensioning member 12 to the outer position, and is connected to a screw 14 near pivot 11, and also to a screw 16 on an inner part of guide means 1. Due to the fact that the springs are disposed eccentric to the respective pivot 11, they exert on the respective tensioning member 12 a turning moment which urges the same to the outer position. At the same time, each spring urges the respective tensioning member 12 together with pivot 11 and guide member 3 to move downward in a working stroke.

During rotation of guide means 1 with tensioning elements 3, 11, 12, 13, cam followers 5 are successively engaged by projecting means of cam 6 so that each tensioning element is retracted in a return stroke against the action of the respective spring 15. When the respective cam follower 5 moves from a higher cam portion down to a lower cam portion, the respective tensioning element is pulled by the respective spring 15 in the downward working stroke during which the tensioning member 12 in its outer position engages fabric 31 to tension the portion of the fabric between the needles and the point of the respective tensioning member, while pushing the fabric downward toward the container, not shown. Cam 6 may have one or several cam projections of different height, and such cam projections are operative irrespective of whether the needle cylinder continuously rotates in one direction, or oscillates as is required for the making of heels of stockings.

A holding means 17 is secured to the center portion of the lower end of guide means 1, and has a plurality of pointed projections 18 arranged in a circle having such a diameter that the pointed projections 18 slide on the inner surface of fabric 31. Holding member 17 rotates with guide means 1, and tensioning members 12 are respectively located in spaces between circumferentially spaced pointed projections 18.

While the pointed projection 18 permits downward movement of fabric 31, particularly under the action of tensioning members 12, the fabric is held by the pointed projections 18 when a loop of the fabric is caught by a pin 13 of a tensioning member during the return stroke of the same. Consequently, the fabric cannot follow tensioning members 12 during the upward return stroke, but is held by holding means 1.

Spring 21 urges support shaft 7 With guide means 1 :and tensioning means 3, 11, 12, 16 upward to an inoperative position in which the pointed ends of tensioning members 12 do not cooperate with the fabric. When the operation of Bowden cable 19, lever urges support shaft down, the apparatus assumes its operative position, and the rotating needle cylinder 22 rotates tube 2 with guide means 1 and the tensioning means so that the tensioning elements including guide members 3 and tensioning members 12 are successively raised by cam 6 in return strokes, and advanced in working strokes by springs 15. The pins 13 at the ends of tensioning members 12 engage fabric 31, tension the same and transport the same in downward direction. During the return strokes of the tensioning members 12, 13, the fabric is not pulled up since it is retained by the pointed projections 18 of the holding means 17 which rotate with the guide means, fabric and needle cylinder.

Whenever a cam follower roller 5 is engaged by a cam projection and the corresponding guide member 3 with a tensioning member 12 is raised, the tensioned spring 15 turns the respective tensioning member 12 radially inward so that the pin 13 separates from the fabric during the upward stroke of tensioning element 3, 12. As soon as cam follower roller 5 has passed beyond the highest point of the cam projection, spring 15 turns the respective tensioning member 12 outward so that its pin 13 passes into a loop of the fabric establishing a connection between the tensioning member and the fabric for the downward working stroke to the lowest portion of cam 6, and tensioning member 12 remains in the outer position until roller 5 again moves onto a rising cam track portion.

Bowden cable 19' is preferably operated from the pattern drum of the machine so that at the proper moment, cable 19 is released to permit spring 21 to raise the apparatus to an inoperative position in which the pointed ends 13 and 18 are out of engagement with the fabric.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of apparatus for tension ing and transporting a fabric during knitting of the same differing from the types described above.

While the invention has been illustrated and described as embodied in an apparatus including reciprocating successively operating tensioning members for tensioning a tubular fabric passing through the needle cylinder of a circular knitting machine, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a circular knitting machine having a rotary needle cylinder, and making a fabric passing through the interior of said needle cylinder, in combination apparatus for tensioning said fabric, comprising support means; guide means mounted on said support means for rotation about the axis of said needle cylinder and being rotated from the same; tensioning means mounted on said guide means for axial reciprocating movement, and projecting into said needle cylinder so as to engage and tension said fabric during a working stroke, and to release the same during a return stroke; and operating means for reciprocating said tensioning means, said operating means including biassing means connected with said tensioning means and urging the same to move in said working stroke and into engagement with said fabric, and stationary cam means mounted on said support means and engaged by said tensioning means during rotation of said guide means to move said tensioning means in said return stroke and out of engagement with said fabric.

2. An apparatus according to claim 1 wherein said tensioning means includes a guide member mounted on said guide means for axial movement and having cam follower means cooperating with said cam means, and a tensioning member movably mounted on said guide member and connected with said biassing means so that said tensioning member is urged into engagement with said fabric.

3. An apparatus according to claim 2 wherein said tensioning member is located in said needle cylinder inward of the fabric; and including pivot means for mounting said tensioning member on said guide member for angular movement between a radially inner position, and a radially outer position engaging the fabric.

4. An apparatus according to claim 1 wherein said support means include a stationary support and a support shaft mounted on said stationary support for axial movement, and rotatably supporting said guide means; and including control means for moving said support shaft with said guide means and tensioning means between an inoperative position and an operative position.

5. An apparatus according to claim 1 including holding means secured to said guide means for engaging the fabric so as to prevent movement of the fabric with said tensioning means during the return stroke of the same.

6. An apparatus according to claim 5 wherein said holding means has a plurality of pointed projections arranged in a circle coaxial with the said needle cylinder.

7. An apparatus according to claim 1 wherein said tensioning means include a plurality of guide members mounted on said guide means along a circle concentric with said axis, and movable in axial direction, and a plurality of tensioning members pivotally mounted on said guide members, respectively, for angular movement between a radially inner position and a radially outer position, and having pointed ends for engaging said fabric in said outer position; wherein biassing means at said operating means include a plurality of springs respectively connecting said tensioning members with said guide means for urging said tensioning members to said outer position, and for urging the same and said guide members to move in a working stroke in said needle cylinder for tensioning said fabric, and wherein said cam means is secured to said support means and engaged by said guide members during rotation of the same with said guide means so that said guide members and said tensioning members therewith are successively moved by said cam means in return strokes, and by said springs in working strokes.

8. An apparatus according to claim 7 wherein said support means include a stationary support, and a support shaft coaxial with said needle cylinder and supporting said guide means for rotation, said cam means being secured to said support shaft, said support shaft being mounted on said support non-rotatably and axially movable with said guide means; and including control means for moving said support shaft with said guide means and D tensioning means between an inoperative position and an operative position; and a tube secured to said needle cylinder and non-rotatably supporting said guide means for axial movement.

9. An apparatus according to claim 8 and including holding means secured to said guide means and projecting into said needle cylinder in said operative position, said holding means having a plurality of pointed projections arranged in a circle for preventing movement of the fabric with said tensioning members during the return strokes of the same.

10. In a circular knitting machine having a rotatable needle cylinder, and making a fabric passing through the interior of said needle cylinder, in combination, apparatus for tensioning said fabric, comprising mutually independent, axially and radially movable mechanical tensioning members for gripping and tensioning said fabric; means mounting said tensioning members for rotation with said needle cylinder; elastic means for urging said mechanical tensioning members into working positions engaging said fabric; stationary cam means cooperating with said mechanical tensioning members due to the rotary motion of the same for moving said tensioning members into inoperative positions; and holding means for holding said knitted fabric in a tensioned condition during the movement of said mechanical tensioning members to said inoperative positions, said holdng means having an axially immovable working position.

References Cited UNITED STATES PATENTS 1,885,322 11/1932 Bentley et al. 6614 2,345,698 4/1944 Bromley et al 66l50 2,396,656 3/1946 Holmes 66150 2,406,285 8/1946 Fregeolle 66150 2,408,807 10/1946 Norman 66-150 XR 2,506,968 5/1950 Oberholtzer 66150 XR 2,521,258 9/1950 Semotan 66-150 2,763,145 9/1956 St. Pierre 66-15O 3,277,672 10/1966 Oliver 66149 XR 3,292,394 12/1966 Luchi 66-149 FOREIGN PATENTS 863,578 4/1941 France.

MERVIN STEIN, Primary Examiner.

RONALD FELDBAUM, Assistant Examiner. 

